Method for the sharpening of four faces drills and sharpening machine for carrying out this method

ABSTRACT

Apparatus for grinding drill faces. Two grinding wheels having different grained surfaces are adapted to operate on the drill either together or with only one wheel so operable.

D United States Patent 11 1 1111 3,885,925 Tatar May 27, 1975 METHOD FORTHE SHARPENING OF [56] References Cited FOUR FACES DRILLS AND SHARPENINGUNITED S A PATENTS MACHINE FOR CARRYING OUT THIS 2 309 016 1 1943 Ryan51/209 R METHOD 2,594,137 4/1952 Doermann 51/207 2,600,815 6/1952 Turner51/209 R [76] Inventor a a i: R gf of 2,749,684 6/1956 Schuhmann 151/209 R a 2,932,135 4/1960 Tatar 51/124 R France 3,067,551 12 1962Maginnis 51 207 22 Filed: Oct. 17 1973 3,626,436 12/1971 Lhomme 51/124 R[2]] Appl' 407131 Primary Examiner-Al Lawrence Smith 7 AssistantExaminerK. J. Ramsey 30 Foreign Application p i i Data Attorney, Agent,or FirmSilverman & Cass Ltd.

Oct. 23, 1972 Switzerland 15461/72 [57] ABSTRACT [52] US. Cl 51/122;51/124 R; 51/288; Apparatus for grinding drill faces Two grinding 51/327wheels having different grained surfaces are adapted [51] Int. Cl B24)5/36 to perate on the drill either together or with only one 0f SearchR, 124 R, 122, 288, wheel so operable 5 Claims, 5 Drawing Figures METHODFOR THE SHARPENING OF FOUR FACES DRILLS AND SHARPENING MACHINE FORCARRYING OUT THIS METHOD BACKGROUND OF THE INVENTION The object of thepresent invention is to provide a method for sharpening four faceddrills by means of two grinding wheels of two different grains, and toprovide a sharpening machine for carrying out of said method.

SUMMARY OF THE INVENTION The method according to the invention ischaracterized by the fact that, for each pair of faces of a four faceddrill to be sharpened, the drill having cutting and clearance faces, onemay urge the drill to pass a first time opposite two grinding wheels,one of which, having the thinnest grain, is then situated back from thealignment of the working plane of the other grinding wheel, such thatonly the last named wheel which has the roughest grain, contacts thedrill and shapes the clearance face thereof; thereafter, the drill maybe urged to'pass anew opposite the two grinding wheels, during a reversemovement, after a relative movement between the drill and the grindingwheels has been effected, such that the grinding wheel then contacts thecutting face of the drill after the two grinding wheels have beenbrought into a same plane. During this reverse displacement of thedrill, the grinding wheel having the roughest grain shapes first thecutting face of the drill and the grinding wheel having the thinnestgrain finishes the operation on this same face.

The machine constructed in accord the invention is characterized by thefact that it comprises two grinding wheels having different grainsmounted in such a way as to be able to effect a relative movement suchthat they can occupy a position in which only the grinding wheel havingthe roughest grain is able to work, and a position in which both areable to work. Means are provided to permit the drill to move opposite tothe said grinding wheels and means synchronizing the movements of thegrinding wheels and of the drill are provided so that, in one directionof the displacements of the drill opposite the grinding wheels, only thegrinding wheel having the roughest grain makes contact with the ,drillwhile, in the reverse direction, the two grinding wheels operatesuccessively, the one having the roughest grain first attacking thedrill and the one having the thinnest grain then finishing the work.

The drawing shows, by way of example, one embodiment of apparatusconstructed in accordance with the invention, and one modificationthereof.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial axial sectionalview of a sharpening machine for four faced drills.

FIGS. 2 and 3 are sectional views of a detail, in two different workingpositions, showing the sharpening processes, and

FIGS. 4 and 5 are sectional views of a detail of a modification,corresponding respectively to FIGS. 2 and 3 of the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present machine, the onlyelements of which are shown in the drawing are those necessary to theunderstanding of the invention, comprises a quill 1 adapted to rotate ina headstock 2. Quill l carries at one of its ends, a pulley 3 driven bya belt 4 which is itself driven by a motor not shown. The quill lcarries, at its opposite end, the hub 5 of a bell shaped grinding wheel6.

The hub 5 carries, freely mounted thereon, a plate 7 which itselfcarries a bell shaped grinding wheel 8, the grain of which is thinnerthan that of the grinding wheel 6. Three coil springs 9, only one ofwhich is visible in the drawing, urge the plate 7 to maintain the samein bearing engagement against a ring 10 screwed on the hub 5, in aposition in which the working plane 11 of the grinding wheel 8 issituated back from the alignment therewith of the working plane 12 ofthe grinding wheel 6. A driving finger 13 carried by the hub 5 and whichis engaged in a hole of the plate 7 renders the plate angularly rigidwith the hub 5, in such a way that the two grinding wheels are rotatablydriven by the quill 1.

The quill is traversed by two sliding rods 14 connected at their rearends by a yoke 15 and which are engaged, at their front ends, in a ring16 which is in contact, by the intermediary of roller bearing 17, withthe plate 7. A pusher 18 is controlled by an electromagnet, the coil 19of which (diagrammatically shown), acts on the yoke 15 for moving ittowards the right side of FIG. 1. Yoke 15 operates rods 14 to move ring16 and bearings 17 against plate 7 to force plate 7 toward the right asviewed in FIG. 1, against the action of the springs 9, bringing thegrinding wheel 8 into a position in which its working plane 11 coincideswith the working plane 12 of the grinding wheel 6.

The machine disclosed and represented operates as follows:

A four faced drill, such as drill 20 of FIG. 2 and 3, is moved oppositethe two grinding wheels in the direction of the arrow 21 of FIG. 2 whilethe grinding wheels occupy their relative position in which the grindingwheel 8 is eclipsed and only grinding wheel 6 is able to work. The axisof the drill then occupies the position indicated by I in FIGS. 2 and 3.During this movement of the drill, the grinding wheel 6, the grain ofwhich is rougher than that of wheel 8 shapes one of the clearance facesof the drill, which face is designated by 22.

The drill is then rocked or pivoted with respect to the working plane ofthe grinding wheel so that the axis of the drill occupies the positionindicated at II in FIGS. 2 and 3, while the grinding wheel 8 is advancedso that its working plane coincides with that of the grinding wheel 6.The synchronisation of the movements is obtained, for instance, by meansof a micro-switch feeding the coil 19 of the electro-magnet controllingthe pusher 18, which microswitch is itself operated for instance by thecarriage, not represented, which carries the drill 20 and which producesits movements opposite the grinding wheel.

During the reverse movement of the drill, in the direction of the arrow23 of FIG. 3, one of the cutting faces 24 of the drill is first shapedby the grinding wheel 6, the grain of which is rougher than that ofwheel 8, then polished by the grinding wheel 8 the grain of which isthinner than that of wheel 6.

it is to be noted that the relative movement between the grinding wheeland the drill which is effected after the first displacement of thedrill, so as to present its cutting face after its clearance face intocontact with the grinding wheels. can be effected instead of beingobtained by a rocking movement of the drill by rocking the two grindingwheels. This rocking is possible if the headstock 2 of the quill l isarticulated on the frame of the machine.

ifhe modification described above is represented in FIGS. 4 and 5 inwhich. as it can be seen, the axis of the tirill maintains its directionunchanged while, on the contrary. the grinding wheels 6 and 8 have theirworktng plane situated in a position l in FIG 4 and in a position ll inFIG. 5. the passage from one to the other peing obtained by a rockingmovement through the grinding wheels. of an angle equivalent to theangle be tween the two positions l and II of the drill 20 in FIGS. l and2.

What I claim is:

l. Method for sharpening a four faced drill having pairs of cutting andclearance faces. the sharpening being effected with two grinding wheelsrespectively having grinding surfaces of different grain roughnesses,581d method comprising the steps of: positioning the grinding wheelsrelative to each other such that only the wheel with the rougher grainis operable on a drill tace, positioning the drill relative to thewheels to present a clearance face thereof for sharpening, urging thedrill to pass opposite the two grinding wheels in one direction suchthat the clearance face thereof contacts only the rougher grain wheel,next positioning the wheels relative to each other such that both wheelsare operable on a drill face, re-positioning the drill relative to thewheels to present a cutting face thereof for sharpening, and moving thedrill in a direction opposite to said one direction such that thecutting face of the drill contacts first the rougher grain wheel andimmediately thereafter the thinner grain wheel to finish the sharpeningof the cutting face of the drill.

2. Method as claimed in claim 1 in which said repositioning of the drillafter sharpening of the clearance face is achieved by rocking movementof the drill.

3. Method as claimed in claim 1 in which said repositioning of the drillafter sharpening of the clearance face is achieved by rocking movementof the two grinding wheels.

4. Machine for sharpening a four faced drill comprising, two grindingwheels respectively having grinding surfaces of different grainroughnesses. said wheels being cooperatively mounted for movement onerelative the other to alternatively occupy a first position in whichonly the grinding wheel having the rougher grain surface is operable onthe drill and a second position in which both wheels are so operable,means for moving the drill opposite said wheels, and means forsynchronizing the movement of the grinding wheels and the drill, wherebyin one direction of displacement of the drill opposite the grindingwheels only the grinding wheel having the rougher grain surface makescontact with the drill and in the reverse direction of displacement ofthe drill the two wheels operate successively on the drill such that thewheel having the rougher grain surface first makes contact with thedrill and immediately thereafter the wheel having the thinner grainsurface makes contact with the drill to finish the sharpening of thedrill.

5. Machine is claimed in claim 4 in which said grinding wheels are ofgenerally bell-shaped configuration and are mounted concentrically onewith the other, the wheel with the thinner grain surface beingpositioned surrounding the wheel with the rougher grain surface andbeing moveable axially relative to the wheel with the rougher grainsurface between a first eclipsed position in which the working plane ofthe thinner grain grinding surface is positioned behind the workingplane of the wheel with the rougher grain grinding surface and a secondposition in which the grinding surfaces of the two wheels are in thesame working plane.

1. Method for sharpening a four faced drill having pairs of cutting andclearance faces, the sharpening being effected with two grinding wheelsrespectively having grinding surfaces of different grain roughnesses,said method comprising the steps of: positioning the grinding wheelsrelative to each other such that only the wheel with the rougher grainis operable on a drill face, positioning the drill relative to thewheels to present a clearance face thereof for sharpening, urging thedrill to pass opposite the two grinding wheels in one direction suchthat the clearance face thereof contacts only the rougher grain wheel,next positioning the wheels relative to each other such that both wheelsare operable on a drill face, re-positioning the drill relative to thewheels to present a cutting face thereof for sharpening, and moving thedrill in a direction opposite to said one direction such that thecutting face of the drill contacts first the rougher grain wheel andimmediately thereafter the thinner grain wheel to finish the sharpeningof the cutting face of the drill.
 2. Method as claimed in claim 1 inwhich said re-positioning of the drill after sharpening of the clearanceface is achieved by rocking movement of the drill.
 3. Method as claimedin claim 1 in which said re-positioning of the drill after sharpening ofthe clearance face is achieved by rocking movement of the two grindingwheels.
 4. Machine for sharpening a four faced drill comprising, twogrinding wheels respectively having grinding surfaces of different grainroughnesses, said wheels being cooperatively mounted for movement onerelative the other to alternatively occupy a first position in whichonly the grinding wheel having the rougher grain surface is operable onthe drill and a second position in which both wheels are so operable,means for moving the drill opposite said wheels, and means forsynchronizing the movement of the grinding wheels and the drill, wherebyin one direction of displacement of the drill opposite the grindingwheels only the grinding wheel having the rougher grain surface makescontact with the drill and in the reverse direction of displacement ofthe drill the two wheels operate successively on the drill such that thewheel having the rougher grain surface first makes contact with thedrill and immediately thereafter the wheel having the thinner grainsurface makes contact with the drill to finish the sharpening of thedrill.
 5. Machine is claimed in claim 4 in which said grinding wheelsare of generally bell-shaped configuration and are mountedconcentrically one with the other, the wheel with the thinner grainsurface being positioned surrounding the wheel with the rougher grainsurface and being moveable axially relative to the wheel with therougher grain surface between a first eclipsed position in which theworking plane of the thinner grain grinding surface is positioned behindthe working plane of the wheel with the rougher grain grinding surfaceand a second position in which the grinding surfaces of the two wheelsare in the same working plane.